Sensory symptoms are among the most commonly reported associated features of autism spectrum disorders (ASD). Sensory abilities develop more rapidly than social and communication skills, and thus if their dysfunction is better understood in ASD, could serve an important role in early identification and intervention. Altered tactile sensitivity is one of the most typical variants of sensory features, but is paradoxically understudied relative to hearing and vision in ASD. The sense of touch in early infancy lays the foundation for the development of communication and social reward throughout development. Thus, a better understanding of tactile dysfunction in ASD is critical. Most experimental work has investigated discriminative touch on the palmar surface of the hand, usually the fingertip. Affiliative or affective touch is believed to be mediated by a unique class of somatosensory afferent (CT fiber) that is absent in the palm. The proposed project undertakes the examination of affective tactile perception in ASD using converging behavioral, neurophysiological, and neuroanatomical techniques. Observational measures of tactile defensiveness will be correlated with diffusion tensor imaging (DTI) data characterizing the strength of thalamocortical circuits, as well as responses from functional magnetic resonance imaging (fMRI) and event-related potentials (ERP) that will elucidate the spatial and temporal characteristics, respectively, of neural response to affective tactile stimuli in ASD. This study of the neurobehavioral basis of affective touch in ASD will add to the existing experimental literature that is primarily focused on discriminative touch, and will complement the existing behavioral literature by exploring neural mechanisms. A better understanding of tactile sensitivity in ASD has significant potential for developing biomarkers for early identification and as a foundation for efficacy studies of sensory-based treatments of ASD. PUBLIC HEALTH RELEVANCE: This project addresses tactile defensiveness in autism spectrum disorders (ASD), which is not only a source of stress for affected individuals and their families, but may provide important clues to the core features of ASD. The project uses converging approaches to answer the question of what aspects of neural structure and function are associated with tactile defensiveness and response to social touch in ASD. The project is expected to provide a better understanding of the under-studied area of tactile perception in ASD, which will eventually lead to new approaches for treatment and early identification.